Colored glass plate and method for its production

ABSTRACT

To provide a colored glass plate which, despite the content of expensive cerium controlled to be low, simultaneously satisfies low solar transmittance, high visible light transmittance and low UV transmittance, while transmitted light has a green color tone. The colored glass plate comprises, as represented by mass percentage based on oxides, SiO 2 : from 65 to 75%, Al 2 O 3 : from 0 to 6%, MgO: from 0 to 6%, CaO: from 5 to 15%, total iron calculated as Fe 2 O 3 : from 0.3 to 1.2%, total titanium calculated as TiO 2 : from 0.2 to 1.1%, total vanadium calculated as V 2 O 5 : from 0.02 to 0.3%, and total cerium calculated as CeO 2 : from 0.01 to 0.5%, and contains substantially no cobalt, chromium or manganese.

TECHNICAL FIELD

The present invention relates to a colored glass plate whichsimultaneously satisfies low solar transmittance, high visible lighttransmittance and low UV transmittance, while transmitted light has agreen color tone, and a method for its production.

BACKGROUND ART

As a glass plate for automobiles, a colored glass plate (e.g. aheat-absorbing glass plate or a UV-absorbing glass plate) is known,which contains a colorant component whereby transmitted light has agreen or blue color tone.

For such a colored glass plate, the solar transmittance is required tobe low (e.g. the value, as calculated in a thickness of 4 mm, of solartransmittance (hereinafter referred to also as Te) stipulated in JISR3106 (1998) is required to be at most 55%). Further, the visible lighttransmittance is required to be high (e.g. the value, as calculated in athickness of 4 mm, of visible light transmittance (illuminant A, 2degrees field of vision) (hereinafter referred to also as Tv) stipulatedin JIS R3106 (1998) is required to be at least 70%). Further, theUV-transmittance is required to be low (e.g. the value, as calculated ina thickness of 4 mm, of UV-transmittance (hereinafter referred to alsoas Tuv) stipulated in ISO-9050 is required to be at most 12%).

Further, as such a colored glass plate, a glass plate tends to bepreferred such that when a passenger watches the scenery through theglass plate, the color tone of the transmitted light has a green colortone being a more natural color tone (e.g. the dominant wavelength(hereinafter referred to as also as Dw) of transmitted light stipulatedin JIS Z8701 (1982) is from 540 to 570 nm).

Further, for such a colored glass plate, it is desired that types ofcolorant components be reduced as far as possible and that unit pricesof raw materials for colorant components be low, from the viewpoint ofcosts and with a view to preventing inclusion of impurities at the timeof changing the base material (i.e. changing the product type) in themelting furnace to be used for the production of glass.

As colored glass plates whereby transmitted light has a green colortone, for example, the following (1) to (3) have been proposed.

(1) Green glass comprising, per 100 parts by mass of a soda lime silicaglass matrix composition,

-   -   total iron calculated as Fe₂O₃: from 0.5 to 2.0 parts by mass,    -   total titanium calculated as TiO₂: more than 1.0 part by mass        and at most 3.0 parts by mass,    -   CoO: from 0.003 to 0.02 part by mass,    -   Se: from 0 to 0.0008 part by mass,    -   total chromium calculated as Cr₂O₃: from 0 to 0.05 part by mass,    -   total vanadium calculated as V₂O₅: from 0 to 0.5 part by mass,        and    -   total cerium calculated as CeO₂: from 0 to 0.5 part by mass,        wherein the mass proportion of bivalent iron calculated as Fe₂O₃        in the total iron calculated as Fe₂O₃ is from 31 to 50%.

(2) UV-absorbing green glass made substantially of soda lime silicaglass and comprising, as represented by mass percentage based on oxides,

-   -   total iron calculated as Fe₂O₃: from 0.45 to 0.491%,    -   total cerium calculated as CeO₂: from 1.09 to 1.2%,    -   total titanium calculated as TiO₂: from 0.3 to 0.39%, and    -   CoO: from 0 to 0.0003%,        wherein the mass proportion of bivalent iron calculated as Fe₂O₃        in the total iron calculated as Fe₂O₃ is from 30.5 to 32.0%.

(3) UV-absorbing green glass made substantially of soda lime silicaglass and comprising, as represented by mass percentage based on oxides,

-   -   total iron calculated as Fe₂O₃: from 0.52 to 0.63%,    -   total cerium calculated as CeO₂: from 0.9 to 2%,    -   total titanium calculated as TiO₂: from 0.2 to 0.6%, and    -   CoO: from 0 to 0.002%,        wherein the mass proportion of bivalent iron calculated as Fe₂O₃        in the total iron calculated as Fe₂O₃ is from 31 to 38%.

However, the green glass of (1) has a problem such that since thecontent of CoO is large, Tv is low, and Dw is also low (i.e. transmittedlight is bluish green). On the other hand, in the case of theUV-absorbing green glasses of (2) and (3), the content of CoO is small,and the content of total cerium calculated as CeO₂ is large, whereby Tvis high, and Tuv is sufficiently low.

However, recently, the prices for cerium raw materials have gone up, andaccordingly the cost for green glass having a large content of totalcerium calculated as CeO₂ has gone up. Therefore, a colored glass plateis desired which, despite the content of cerium controlled to be low,simultaneously satisfies low solar transmittance, high visible lighttransmittance and low UV transmittance, while transmitted light has agreen color tone.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent No. 3,256,243

Patent Document 2: Japanese Patent No. 3,900,550

Patent Document 3: Japanese Patent No. 3,190,965

DISCLOSURE OF INVENTION Technical Problem

The present invention is to provide a colored glass plate which, despitethe content of expensive cerium controlled to be low, simultaneouslysatisfies low solar transmittance, high visible light transmittance andlow UV transmittance, while transmitted light has a green color tone.

Solution to Problem

The colored glass plate of the present invention is characterized bycomprising, as represented by mass percentage based on oxides,

-   -   SiO₂: from 65 to 75%,    -   Al₂O₃: from 0 to 6%,    -   MgO: from 0 to 6%,    -   CaO: from 5 to 15%,    -   total iron calculated as Fe₂O₃: from 0.3 to 1.2%,    -   total titanium calculated as TiO₂: from 0.2 to 1.1%,    -   total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and    -   total cerium calculated as CeO₂: from 0.01 to 0.5%,        and containing substantially no cobalt, chromium or manganese.

The colored glass plate of the present invention preferably furthercontains, as represented by mass percentage based on oxide, from 5 to18% of Na₂O.

The colored glass plate of the present invention preferably has

-   -   a solar transmittance (Te) as stipulated in JIS R3106 (1998) of        at most 55% as a value calculated in a thickness of 4 mm,    -   a visible light transmittance (Tv) (illuminant A, 2 degrees        field of vision) as stipulated in JIS R3106 (1998) of at least        70% as a value calculated in a thickness of 4 mm,    -   an UV transmittance (Tuv) as stipulated in ISO-9050 of at most        12% as a value calculated in a thickness of 4 mm, and    -   a dominant wavelength (Dw) of transmitted light as stipulated in        JIS Z8701 (1982) of from 540 to 570 nm.

The method for producing a colored glass plate of the present invention,comprises melting glass raw materials, followed by forming to obtain acolored glass plate comprising, as compositional components of the glassplate after the forming and as represented by mass percentage based onoxides,

-   -   SiO₂: from 65 to 75%,    -   Al₂O₃: from 0 to 6%,    -   MgO: from 0 to 6%,    -   CaO: from 5 to 15%,    -   total iron calculated as Fe₂O₃: from 0.3 to 1.2%,    -   total titanium calculated as TiO₂: from 0.2 to 1.1%,    -   total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and    -   total cerium calculated as CeO₂: from 0.01 to 0.5%,        and containing substantially no cobalt, chromium or manganese.

In the method for producing a colored glass plate of the presentinvention, it is preferred that the glass plate further contains, as itscompositional component and as represented by mass percentage based onoxide, from 5 to 18% of Na₂O.

In the method for producing a colored glass plate of the presentinvention, it is preferred to obtain the colored glass plate which has

a solar transmittance (Te) as stipulated in JIS R3106 (1998) of at most55% as a value calculated in a thickness of 4 mm,

a visible light transmittance (Tv) (illuminant A, 2 degrees field ofvision) as stipulated in JIS R3106 (1998) of at least 70% as a valuecalculated in a thickness of 4 mm,

an UV transmittance (Tuv) as stipulated in ISO-9050 of at most 12% as avalue calculated in a thickness of 4 mm, and

a dominant wavelength (Dw) of transmitted light as stipulated in JISZ8701 (1982) of from 540 to 570 nm.

The above expression “to” to represent a numerical range, is used toinclude the numerical values given before and after the expression asthe lower limit value and the upper limit value, respectively, andhereinafter in this specification, the same expression “to” is used tohave the same meaning, unless otherwise specified.

Advantageous Effects of Invention

The colored glass plate of the present invention, despite the content ofexpensive cerium controlled to be low, simultaneously satisfies lowsolar transmittance, high visible light transmittance and low UVtransmittance, while transmitted light has a green color tone.

DESCRIPTION OF EMBODIMENTS

The colored glass plate of the present invention is one containing SiO₂as the main component, and it is preferably one made of so-called sodalime silica glass which further contains Na₂O, CaO, etc.

The colored glass plate of the present invention has the followingcomposition (I). The colored glass plate of the present inventionpreferably has the following composition (II), more preferably has thefollowing composition (III), further preferably has the followingcomposition (IV).

(I) A composition comprising, as represented by mass percentage based onthe following oxides,

-   -   SiO₂: from 65 to 75%,    -   Al₂O₃: from 0 to 6%,    -   MgO: from 0 to 6%,    -   CaO: from 5 to 15%,    -   total iron calculated as Fe₂O₃: from 0.3 to 1.2%,    -   total titanium calculated as TiO₂: from 0.2 to 1.1%,    -   total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and    -   total cerium calculated as CeO₂: from 0.01 to 0.5%,        and containing substantially no cobalt, chromium or manganese.

(II) A composition comprising, as represented by mass percentage basedon the following oxides,

-   -   SiO₂: from 65 to 75%,    -   Al₂O₃: from 0 to 6%,    -   MgO: from 0 to 6%,    -   CaO: from 5 to 15%,    -   Na₂O: from 5 to 18%,    -   total iron calculated as Fe₂O₃: from 0.3 to 1.2%,    -   total titanium calculated as TiO₂: from 0.2 to 1.1%,    -   total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and    -   total cerium calculated as CeO₂: from 0.01 to 0.5%,        and containing substantially no cobalt, chromium or manganese.

(III) A composition comprising, as represented by mass percentage basedon the following oxides,

-   -   SiO₂: from 68 to 73%,    -   Al₂O₃: from 0.5 to 3.5%,    -   MgO: from 2 to 6%,    -   CaO: from 6 to 11%,    -   Na₂O+K₂O: from 10 to 18%,    -   total iron calculated as Fe₂O₃: from 0.5 to 0.9%,    -   total titanium calculated as TiO₂: from 0.5 to 1.0%,    -   total vanadium calculated as V₂O₅: from 0.05 to 0.20%, and    -   total cerium calculated as CeO₂: from 0.05 to 0.30%,        and containing substantially no cobalt, chromium or manganese.

(IV) A composition comprising, as represented by mass percentage basedon the following oxides,

-   -   SiO₂: from 70 to 72%,    -   Al₂O₃: from 1.5 to 2.0%,    -   MgO: from 2.5 to 5%,    -   CaO: from 7 to 9%,    -   Na₂O+K₂O: from 11 to 16%,    -   total iron calculated as Fe₂O₃: from 0.6 to 0.8%,    -   total titanium calculated as TiO₂: from 0.7 to 0.9%,    -   total vanadium calculated as V₂O₅: from 0.06 to 0.09%, and    -   total cerium calculated as CeO₂: from 0.08 to 0.20%,        and containing substantially no cobalt, chromium or manganese.

The colored glass plate of the present invention is characterized inthat Tuv is maintained to be low by replacing a part of cerium byvanadium, Te is lowered by incorporating iron, and Tv is made high whilemaking Dw to be from 540 to 570 nm as desired, by adjusting the contentof total iron calculated as Fe₂O₃, the content of total titaniumcalculated as TiO₂, the content of total vanadium calculated as V₂O₅ andthe content of total cerium calculated as CeO₂.

The content of total iron calculated as Fe₂O₃ is from 0.3 to 1.2%, asrepresented by mass percentage based on oxide. When the content of totaliron calculated as Fe₂O₃ is at least 0.3%, it is possible to lower Te.As content of total iron calculated as Fe₂O₃ increases, Te lowers, butTv also lowers. When the content of total iron calculated as Fe₂O₃ ismade to be at most 1.2%, it is possible to prevent lowering of Tv and tobring Tv to be at least 70% (as calculated in a thickness of 4 mm). Thecontent of total iron calculated as Fe₂O₃ is preferably from 0.5 to0.9%, more preferably from 0.6 to 0.8%, as represented by masspercentage based on oxide.

The content of total titanium calculated as TiO₂ is from 0.2 to 1.1%, asrepresented by mass percentage based on oxide. When the content of TiO₂is at least 0.2%, it is possible to adjust Dw to be at least 540 nm.Further, it is possible to lower Tuv. When the content of TiO₂ is atmost 1.1%, it is possible to adjust Dw to be at most 570 nm. Further, itis possible to make Tv to be high. The content of total titaniumcalculated as TiO₂ is preferably from 0.5 to 1.0%, more preferably from0.7 to 0.9%, as represented by mass percentage based on oxide.

The content of total vanadium calculated as V₂O₅ is from 0.02 to 0.3%,as represented by mass percentage based on oxide. When the content ofV₂O₅ is at least 0.02%, it is possible to lower Tuv. When the content ofV₂O₅ is at most 0.3%, it is possible to make Tv to be high. The contentof total vanadium calculated as V₂O₅ is preferably from 0.05 to 0.20%,more preferably from 0.06 to 0.09%, as represented by mass percentagebased on oxide.

The content of total cerium calculated as CeO₂ is from 0.01 to 0.5%, asrepresented by mass percentage based on oxide. When the content of CeO₂is at least 0.01%, it is possible to lower Tuv. When the content of CeO₂is at most 0.5%, it is possible to suppress the cost of the coloredglass plate, and to make Tv to be high. The content of total ceriumcalculated as CeO₂ is preferably from 0.05 to 0.30%, more preferablyfrom 0.08 to 0.20%, further preferably from 0.09 to 0.13%, asrepresented by mass percentage based on oxide.

The colored glass plate of the present invention contains substantiallyno cobalt, chromium or manganese which has, heretofore, been used as atypical colorant component. Here, “contains substantially no cobalt,chromium or manganese” means that cobalt, chromium or manganese is notcontained at all, or cobalt, chromium or manganese may be contained asimpurities unavoidably included during the production. When cobalt,chromium or manganese is not contained substantially, Tv can be madehigh, it is possible to prevent inclusion of impurities at the time ofchanging the base material, and the cost for the colored glass plate canbe suppressed. The content of such impurities may vary depending uponthe glass raw material to be used, but in the case of a glass plate forautomobiles or buildings, it is preferably made to be less than 0.1%,more preferably less than 0.05%, further preferably less than 0.01%, asrepresented by mass percentage.

Here, “inclusion of impurities at the time of changing the basematerial” means the following.

During its production, glass may sometimes be switched to another glasstype having a different glass composition (i.e. change of the basematerial). The inclusion of impurities at the time of changing the basematerial means that at the time of switching to another glass type,components of the glass before switching are included into the glassafter switching. If inclusion of impurities such as cobalt, chromium,manganese, etc., takes place, after the switching, the color tone of theglass will be thereby substantially influenced.

SiO₂ is the main component of glass.

The content of SiO₂ is, as represented by mass percentage based onoxide, from 65 to 75%. When the content of SiO₂ is at least 65%, theweather resistance will be good. When the content of SiO₂ is at most75%, devitrification is less likely to take place. The content of SiO₂is, as represented by mass percentage based on oxide, preferably from 68to 73%, more preferably from 70 to 72%.

Al₂O₃ is a component to improve the weather resistance.

The content of Al₂O₃ is, as represented by mass percentage based onoxide, from 0 to 6%. When the content of Al₂O₃ is at most 6%, themelting properties will be good. The content of Al₂O₃ is, as representedby mass percentage based on oxide, preferably from 0.5 to 3.5%, morepreferably from 1.5 to 2.0%.

MgO is a component to accelerate melting of the glass raw material andto improve the weather resistance.

The content of MgO is, as represented by mass percentage based on oxide,from 0 to 6%. When the content of MgO is at most 6%, devitrification isless likely to take place.

The content of MgO is, as represented by mass percentage based on oxide,preferably from 2 to 6%, more preferably from 2.5 to 5%, furtherpreferably from 3 to 4%, since the glass matrix composition raw materialis thereby easily available, and it is possible to lower the cost of thecolored glass plate.

On the other hand, a colored glass plate wherein the content of MgO isless than 2%, has lower Te, as compared with a colored glass platewherein the content of MgO is at least 2%, at the same Tv. Therefore,when the content of MgO is less than 2%, it is possible to easilyimprove the heat ray absorption without impairing the visible lighttransmittance. The content of MgO is, as represented by mass percentagebased on oxide, preferably at least 0% and less than 2%, more preferablyfrom 0 to 1.0%, further preferably from 0 to 0.5%, with a view tosufficiently lowering Te while suppressing a decrease of Tv by theaddition of a colorant component.

CaO is a component to accelerate melting of the glass raw material andto improve the weather resistance.

The content of CaO is, as represented by mass percentage based on oxide,from 5 to 15%. When the content of CaO is at least 5%, the meltingproperties and weather resistance will be good. When the content of CaOis at most 15%, devitrification is less likely to take place. Thecontent of CaO is, as represented by mass percentage based on oxide,preferably from 6 to 11%, more preferably from 7 to 9%.

The colored glass plate of the present invention may contain SrO inorder to accelerate melting of the glass raw material. The content ofSrO is, as represented by mass percentage based on oxide, preferablyfrom 0 to 5%, more preferably from 0 to 3%. When the content of SrO isat most 5%, the melting of the glass raw material can sufficiently beaccelerated.

The colored glass plate of the present invention may contain BaO inorder to accelerate melting of the glass raw material. The content ofBaO is, as represented by mass percentage based on oxide, preferablyfrom 0 to 5%, more preferably from 0 to 3%. When the content of BaO isat most 5%, the melting of the glass raw material can sufficiently beaccelerated.

The colored glass plate of the present invention preferably containsNa₂O and K₂O, or Na₂O, in order to accelerate melting of the glass rawmaterial. The total content of Na₂O and K₂O is, as represented by masspercentage based on oxides, preferably from 10 to 18%, more preferablyfrom 11 to 16%, further preferably from 12 to 14%. When the content ofNa₂O+K₂O is at least 10%, the melting properties will be good. When thecontent of Na₂O+K₂O is at most 18%, the weather resistance will be good.

The content of Na₂O is, as represented by mass percentage based onoxide, preferably from 5 to 18%, more preferably from 10 to 16%, furtherpreferably from 12 to 15%.

The content of K₂O is, as represented by mass percentage based on oxide,preferably from 0 to 5%, more preferably from 0.2 to 1%, furtherpreferably from 0.2 to 0.4%.

The colored glass plate of the present invention may contain SO₃ used asa fining agent. The content of SO₃ is, as represented by mass percentagebased on oxide, preferably from 0 to 1%, more preferably from 0.01 to0.5%, further preferably from 0.05 to 0.2%. When the content of SO₃ isat most 1%, the gas component of SO₂ is less likely to remain as gasbubbles in glass.

The colored glass plate of the present invention may contain SnO₂ usedas a fining agent. The content of SnO₂ is, as represented by masspercentage based on oxide, preferably from 0 to 0.5%, more preferablyfrom 0 to 0.3%, further preferably from 0 to 0.1%. When the content ofSnO₂ is at most 0.5%, volatilization of SnO₂ tends to be less, and it ispossible to suppress the cost to be low.

The specific gravity of the colored glass plate of the present inventionis preferably from 2.49 to 2.55, more preferably from 2.50 to 2.52. Bybringing the specific gravity of the colored glass plate of the presentinvention to be equal to usual soda lime silica glass, it is possible toimprove the efficiency for changing the composition (i.e. changing thebase material) at the time of the production.

The specific gravity of the colored glass plate of the present inventioncan be adjusted by adjusting the glass matrix composition. To adjust thespecific gravity to the above level, the mass ratio ofSiO₂/(MgO+CaO+SrO+BaO) is made to be preferably from 5.0 to 8.0, morepreferably from 5.5 to 6.5. Here, (MgO+CaO+SrO+BaO) represents the totalcontent of MgO, CaO, SrO and BaO which are contained.

Te (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at most 55%, preferably at most 52%, morepreferably at most 50%. Te is a solar transmittance calculated bymeasuring the transmittance by a spectrophotometer in accordance withJIS R3106 (1998) (hereinafter referred to simply as JIS R3106).

Tv (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at least 70%, preferably at least 71.5%. Tv isa visible light transmittance calculated by measuring the transmittanceby a spectrophotometer in accordance with JIS R3106. As the coefficient,a value of standard illuminant A, 2 degrees field of vision is employed.

Tuv (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at most 12%, preferably at most 10%. Tuv is aUV transmittance calculated by measuring the transmittance by aspectrophotometer in accordance with ISO-9050.

The dominant wavelength (Dw) of transmitted light through the coloredglass plate of the present invention is from 540 to 570 nm, preferablyfrom 550 to 560 nm. When the dominant wavelength is within the aboverange, it is possible to obtain a colored glass plate wherebytransmitted light has the desired green color tone. The dominantwavelength is one calculated by measuring the transmittance by aspectrophotometer in accordance with JIS Z8701 (1982). As thecoefficient, a value of standard light C, 2 degrees field of vision isemployed.

The colored glass plate of the present invention may be used for eithervehicles or buildings and is particularly useful as a windshield or doorglass for automobiles. In a case where it is to be used as a windowglass for an automobile, as the case requires, it may be used in theform of laminated glass having a plurality of glass plates laminatedwith an interlayer, glass having flat glass processed to have a curvedsurface, or glass having tempering treatment applied. Otherwise, in acase where it is to be used as double-layered glass for buildings, itmay be used in the form of double-layered glass composed of two coloredglass plates of the present invention, or double-layered glass composedof a colored glass plate of the present invention and another glassplate.

The colored glass plate of the present invention may be produced, forexample, via the following sequential steps (i) to (iv) and, as the caserequires, further via a step (v).

(i) In order to attain a desired glass composition, glass matrixcomposition raw materials such as silica sand, etc., colorant componentraw materials such as an iron source, a titanium source, a vanadiumsource, a cerium source, etc., an oxidizing agent, a reducing agent, afining agent, etc., are suitably mixed to prepare a glass raw material.

(ii) The glass raw material is continuously supplied to a meltingfurnace, heated to from about 1,400 to 1,600° C. (e.g. about 1,500° C.)by heavy oil, etc. and melted to obtain molten glass.

(iii) The molten glass is refined and then formed into a glass platehaving a prescribed thickness by e.g. a float process.

(iv) The glass plate is annealed and then cut into a prescribed size toobtain a colored glass plate of the present invention.

(v) As the case requires, the cut glass plate may be subjected totempering treatment, may be processed into laminated glass, or may beprocessed into double-layered glass.

The glass matrix composition raw materials may be ones commonly used asraw materials for usual soda lime silica glass, such as silica sand, analumina source, a magnesia source, a calcia source, an alkali oxidesource, etc.

The iron source may, for example, be iron powder, iron oxide powder,rouge, etc.

The titanium source may, for example, be titanium oxide, etc.

The vanadium source may, for example, be vanadium oxide, etc.

The oxidizing agent may, for example, be sodium nitrate, etc. Theoxidizing agent is one to accelerate oxidation of iron in molten glass.

The cerium source may, for example, be cerium oxide, etc.

The reducing agent may, for example, be carbon, coke, etc. The reducingagent is one to prevent oxidation of iron in molten glass.

Further, SnO₂ may be used as a reducing agent or a fining agent, and SO₃may be used as an oxidizing agent or a fining agent.

In the colored glass plate of the present invention as described above,as represented by mass percentage based on oxide, total iron calculatedas Fe₂O₃ is from 0.3 to 1.2%, total titanium calculated as TiO₂ is from0.2 to 1.1%, total vanadium calculated as V₂O₅ is from 0.02 to 0.3%, andtotal cerium calculated as CeO₂ is from 0.01 to 0.5%, whereby despitethe content of expensive cerium controlled to be low and containingsubstantially no other colorant components (such as cobalt, etc.), itsatisfies Te≦55% (as calculated in a thickness of 4 mm), Tv≧70% (ascalculated in a thickness of 4 mm) and Tuv≦12% (as calculated in athickness of 4 mm), while transmitted light has a green color tone.

EXAMPLES

Now, the present invention will be described specifically with referenceto Examples, but it should be understood that the present invention isby no means limited to such Examples.

Ex. 1 to 3 are Examples of the present invention, and Ex. 4 is aComparative Example.

(Te)

With respect to an obtained glass plate, the solar transmittance (Te) asstipulated in JIS R3106 was obtained as a value calculated in athickness of 4 mm.

(Tv)

With respect to an obtained glass plate, the visible light transmittance(Tv) (illuminant A, 2 degrees field of vision) as stipulated in JISR3106 was obtained as a value calculated in a thickness of 4 mm.

(Tuv)

With respect to an obtained glass plate, the UV transmittance (Tuv) asstipulated in ISO-9050 was obtained as a value calculated in a thicknessof 4 mm.

(Dw)

With respect to an obtained glass plate, the dominant wavelength (Dw) oftransmitted light as stipulated in JIS Z8701 (1982) was obtained.

Ex. 1 to 4

The respective raw materials were mixed to attain the composition shownin Table 1, and further, Na₂SO₄ was mixed as an oxidizing agent in theamount shown in Table 1 as calculated as SO₃, to prepare a glass rawmaterial. The glass raw material was put in a crucible and heated to1,500° C. in an electric furnace to obtain molten glass. The moltenglass was cast on a carbon plate and cooled. Both sides were polished toobtain a glass plate having a thickness of 4 mm. With respect to theobtained glass plate, the transmittances were measured for every 1 nm bymeans of a spectrophotometer (Lambda 950, manufactured by Perkin Elmer)to obtain Te, Tv, Tuv and Dw. The results are shown in Table 1.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Composition (%) SiO₂ 71.4 71.5 71.3 70.8Al₂O₃ 1.9 1.9 1.9 1.5 MgO 3.7 3.7 3.7 3.9 CaO 8.0 8.0 8.0 8.1 Na₂O 12.913.0 12.9 13.8 K₂O 0.3 0.3 0.3 0.3 Fe₂O₃ 0.70 0.70 0.70 0.81 TiO₂ 0.810.61 0.81 0.42 V₂O₅ 0.07 0.07 0.08 0 CeO₂ 0.10 0.10 0.10 0.09 CoO 0 0 00 Cr₂O₃ 0 0 0 0 MnO 0 0 0 0 Oxidizing agent (%) SO₃ 0.1 0.1 0.2 0.3 Tv(%/4 mmt) 72.5 72.7 72.4 73.2 Te (%/4 mmt) 49.0 48.6 49.0 45.8 Tuv (%/4mmt) 9.9 10.9 9.5 14.9 Dw (nm) 556 551 556 533

The colored glass plate of the present invention in each of Ex. 1 to 3satisfied Te<55% (as calculated in a thickness of 4 mm), Tv>70% (ascalculated in a thickness of 4 mm) and Tuv<12% (as calculated in athickness of 4 mm), while transmitted light had a green color tone withits dominant wavelength being within a range of from 540 to 570 nm.

The colored glass plate in Ex. 4 contained no V₂O₅, whereby Tuv washigh.

INDUSTRIAL APPLICABILITY

The colored glass plate of the present invention is useful as a glassplate for vehicles and buildings, and is particularly suitable as aglass plate for automobiles.

This application is a continuation of PCT Application No.PCT/JP2013/051659, filed on Jan. 25, 2013, which is based upon andclaims the benefit of priority from Japanese Patent Application No.2012-015562 filed on Jan. 27, 2012. The contents of those applicationsare incorporated herein by reference in their entireties.

What is claimed is:
 1. A colored glass plate comprising, as representedby mass percentage based on oxides, SiO₂: from 65 to 75%, Al₂O₃: from 0to 6%, MgO: from 0 to 6%, CaO: from 5 to 15%, total iron calculated asFe₂O₃: from 0.3 to 1.2%, total titanium calculated as TiO₂: from 0.2 to1.1%, total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and totalcerium calculated as CeO₂: from 0.01 to 0.5%, and containingsubstantially no cobalt, chromium or manganese.
 2. The colored glassplate according to claim 1, which further contains, as represented bymass percentage based on oxide, from 5 to 18% of Na₂O.
 3. The coloredglass plate according to claim 1, which has a solar transmittance asstipulated in JIS R3106 (1998) of at most 55% as a value calculated in athickness of 4 mm, a visible light transmittance (illuminant A, 2degrees field of vision) as stipulated in JIS R3106 (1998) of at least70% as a value calculated in a thickness of 4 mm, an UV transmittance asstipulated in ISO-9050 of at most 12% as a value calculated in athickness of 4 mm, and a dominant wavelength of transmitted light asstipulated in JIS Z8701 (1982) of from 540 to 570 nm.
 4. A method forproducing a colored glass plate, which comprises melting glass rawmaterials, followed by forming to obtain a colored glass platecomprising, as compositional components of the glass plate after theforming and as represented by mass percentage based on oxides, SiO₂:from 65 to 75%, Al₂O₃: from 0 to 6%, MgO: from 0 to 6%, CaO: from 5 to15%, total iron calculated as Fe₂O₃: from 0.3 to 1.2%, total titaniumcalculated as TiO₂: from 0.2 to 1.1%, total vanadium calculated as V₂O₅:from 0.02 to 0.3%, and total cerium calculated as CeO₂: from 0.01 to0.5%, and containing substantially no cobalt, chromium or manganese. 5.The method for producing a colored glass plate according to claim 4,wherein the glass plate further contains, as its compositional componentand as represented by mass percentage based on oxide, from 5 to 18% ofNa₂O.
 6. The method for producing a colored glass plate according toclaim 4, wherein the colored glass plate has a solar transmittance asstipulated in JIS R3106 (1998) of at most 55% as a value calculated in athickness of 4 mm, a visible light transmittance (illuminant A, 2degrees field of vision) as stipulated in JIS R3106 (1998) of at least70% as a value calculated in a thickness of 4 mm, an UV transmittance asstipulated in ISO-9050 of at most 12% as a value calculated in athickness of 4 mm, and a dominant wavelength of transmitted light asstipulated in JIS Z8701 (1982) of from 540 to 570 nm.